From 9ac42c500586fa5f10a1f6d22c3f797df11b1f6b Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Fri, 27 Oct 2017 15:37:03 +0200
Subject: [PATCH] unlzma: fix SEGV, closes 10436

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
---
Patch status: upstream commit 9ac42c500586f

 archival/libarchive/decompress_unlzma.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/archival/libarchive/decompress_unlzma.c b/archival/libarchive/decompress_unlzma.c
index a9040877efa0..be4342414435 100644
--- a/archival/libarchive/decompress_unlzma.c
+++ b/archival/libarchive/decompress_unlzma.c
@@ -450,8 +450,12 @@ unpack_lzma_stream(transformer_state_t *xstate)
  IF_NOT_FEATURE_LZMA_FAST(string:)
 			do {
 				uint32_t pos = buffer_pos - rep0;
-				if ((int32_t)pos < 0)
+				if ((int32_t)pos < 0) {
 					pos += header.dict_size;
+					/* bug 10436 has an example file where this triggers: */
+					if ((int32_t)pos < 0)
+						goto bad;
+				}
 				previous_byte = buffer[pos];
  IF_NOT_FEATURE_LZMA_FAST(one_byte2:)
 				buffer[buffer_pos++] = previous_byte;
-- 
2.15.1

